Method and system for free-space imaging display and interface

ABSTRACT

This invention comprises a method and system for displaying free-space, full color, high-resolution video or still images while simultaneously enabling the user to have real-time direct interaction with the visual images. The system comprises a self-generating means for creating a dynamic, non-solid particle cloud by ejecting atomized condensate present in the surrounding air, in a controlled fashion, into an invisible particle cloud. A projection system consisting of an image generating means and projection optics, projects an image onto the particle cloud. Any physical intrusion, occurring spatially within the image region, is captured by a detection system and the intrusion information is used to enable real-time user interaction in updating the image. This input/output (I/O) interface provides a display and computer link, permitting the user to select, translate and manipulate free-space floating visual information beyond the physical constraints of the device creating the image.

This invention is described in my U.S. Provisional Application No.60/392,856 filed on Jul. 1, 2002.

FIELD OF THE INVENTION

This invention relates to augmented reality input/output interfacesinvolving free-space imaging displays, environments, simulation, andinteraction.

BACKGROUND OF THE INVENTION

Current technologies attempt to create the visual perception of afree-floating image through the manipulation of depth cues generatedfrom two-dimensional data employing well-established techniques. A fewexamples of these include stereoscopic imaging via shutter or polarizedglasses, as well as auto-stereoscopic technologies composed oflenticular screens directing light from a conventional display, orreal-imaging devices utilizing concave mirror arrangements. All of thesetechnologies suffer convergence and accommodation limitations. This is afunction of the original two-dimensional image generating data and itsdisparity to its perceived spatial location, resulting in user eyestrainand fatigue due to the difficulty of focusing on an image that does nottruly exist where it is perceived to occur.

In order to resolve this visual limitation, the image and its perceivedlocation must coincide spatially. A well-established method solving thisconstraint is by projection onto an invisible surface that inherentlypossesses a true spatially perceived image location; yet prior artmethods rendered poor image fidelity. Projection onto non-solid screenswas first suggested in 1899 by Just, in U.S. Pat. No. 620,592, where animage was projected onto a simple water screen known in the art as fogscreen projections. Since then, general advancements to image qualityhave been described depending solely on improving the laminar quality ofthe screen directly correlating to image quality. As such in prior art,these methodologies limit the crispness, clarity, and spatial imagestability solely based on the dynamic properties of the screen, whichintrinsically produce a relatively spatially unstable image. Minorscreen fluctuations further compound images distortion. Image fidelitywas further compromised and image aberrations amplified by the easilydiscernible screen detracting from the intended objective of free-spaceimaging. Advancements in this invention allow the device to beself-sustainable, and overcome prior art limitations of image stabilityand fidelity, improve viewing angles, and incorporate additionalinteractive capabilities.

One of the main disadvantages found in prior art was the reliance on asupply of screen generating material. These devices depended on either arefillable storage tank for the screen generating material, or thedevice had to be positioned in or around a large body of water such as alake in order to operate. This limited the operating time of the devicein a closed environment such as in a room required refilling, or aplumbing connection for constant operation. The result severely limitedthe ease of operation, portability, and placement of the device causedby this dependence. Furthermore, some fog screen projection systemschanged the operating environment by over-saturating the surroundingambient air with particulates, such as humidity or other ejected gases.The constant stream of ejected material created a dangerous environment,capable of short-circuiting electronics as well as producing a potentialhealth hazard of mold build-up in a closed space, such as in a room. Thedehumidification process disclosed both in Kataoka's U.S. Pat. No.5,270,752 and Ismo Rakkolainen's WAVE white paper, was not employed tocollect moisture for generating the projection surface screen but ratherto increase laminar performance as a separate detached aspirator. Thepresent invention employs condensate extraction method specifically toserve as a self-sustained particle cloud manufacturing and deliverysystem.

Furthermore in prior art, while the projection surface can be optimizedfor uniformity, thickness, and planarity by improving laminarperformance, the inherent nature of a dynamic system's natural tendencytowards turbulence will ultimately affect the overall imaging clarity orcrispness and image spatial stability such as image fluttering. Theseslight changes caused by common fluctuating air currents and otherenvironmental conditions found in most indoor and outdoor environmentsinduce an unstable screen, thereby affecting the image. Prior artattempted to solve these image degradation and stability issues byrelying on screen refinements to prevent the transition of laminar toturbulent flow. Kataoka's, U.S. Pat. No. 5,270,752 included improvementsto minimize boundary layer friction between the screen and surroundingair by implementing protective air curtains, thereby increasing theejected distance of the screen size while maintaining a relativelyhomogeneous laminar thin screen depth and uniform particulate densityfor a stable image. While a relatively laminar screen can be achievedusing existing methodologies, generating a spatially stable and clearimage is limited by depending solely on improvements to the screen.Unlike projecting onto a conventional physical screen with a singlefirst reflection surface, the virtual projection screen mediuminvariably exhibits thickness and consequently any projection imaged isvisible throughout the depth of the medium. As such, the image is viewedmost clearly when directly in front, on-axis. This is due to theidentical image alignment stacked through the depth of the screen isdirectly behind each other and on-axis with respect to the viewer. Whilethe image is most clearly observed on-axis it suffers a significantviewing limitation on a low particulate (density) screen. In order togenerate a highly visible image on an invisible to near-invisible screenrequired high intensity illumination to compensate for the lowtransmissivity and reflectivity of the screen cloud. This is caused byviewing directly into the bright projection source due to the highintensity illumination to compensate for a low transmissivity andreflectivity of the screen. While in a high particulate count (highdensity) particle cloud scenario a lower intensity illumination cancompensate for the high reflectivity of the screen, this invariablecauses the screen to become visibly distracting as well as require alarger and more powerful system to collect the greater amount ofairborne particulates.

Additional advancements described in this invention automaticallymonitor changing environmental conditions such as humidity and ambienttemperature to adjust cloud density, microenvironment and projectionparameters in order to minimize the visibility of the particle cloudscreen. This invention improves invisibility of the screen and imagecontrast in the multisource embodiment by projecting multiple beams atthe image location to maximize illumination intensity and minimize theindividual illumination source intensities.

Prior art also created a limited clear viewing zone of on or nearon-axis. The projection source fan angle generates an increasinglyoff-axis projection towards the edges of the image, fidelity falls offwhere the front surface of the medium is imaging a slightly offset imagethroughout the depth of the medium with respect to the viewers line ofsight. Since the picture is imaged thru the depth of the screen, theviewer not only sees the intended front surface image as on aconventional screen, but all the unintended illuminated particulatesthroughout the depth of the screen, resulting in an undefined and blurryimage. In this invention, a multisource projection system providescontinuous on-axis illumination visually stabilizing the image andminimizing image flutter.

This invention does not suffer from any of these aforementionedlimitations, by incorporating a self-sustainability particle cloudmanufacturing process, significant advances to imaging projection,advances to the microenvironment improving image fidelity, and includeadditional interactive capabilities.

SUMMARY OF THE INVENTION

This invention provides a method and apparatus for generating truehigh-fidelity full color, high-resolution free-space video or stillimages with interactive capabilities. The composed video or still imagesare clear, have a wide viewing angle, possess additional user inputinteractive capabilities and can render discrete images, each viewedfrom separate locations surrounding the device. All of these attributesare not possible with present augmented reality devices, existing fogscreen projections, current displays or disclosed in prior art.

The system comprises a self-generating means for creating a dynamic,invisible or near invisible, non-solid particle cloud, by collecting andsubsequentially ejecting condensate present in the surrounding air, in acontrolled atomized fashion, into a laminar, semi-laminar or turbulent,particle cloud. A projection system consisting of an image generatingmeans and projection optics, projects an image or images onto saidparticle cloud. The instant invention projects still images or dynamicimages, text or information data onto an invisible to near-invisibleparticle cloud screen surface. The particle cloud exhibits reflective,refractive and transmissive properties for imaging purposes when adirected energy source illuminates the particle cloud. A projectionsystem comprising single or multiple projection sources illuminate theparticle cloud in a controlled manner, in which the particulates orelements of the particle cloud act as a medium where the controlledfocus and intersection of light generate a visible three-dimensionalspatially addressable free-space illumination where the image iscomposed.

Furthermore, any physical intrusion, occurring spatially within theparticle cloud image region, is captured by a detection system and theintrusion such as a finger movement, enables information or image to beupdated and interacted with in real-time. This input/output (I/O)interface provides a novel display and computer interface, permittingthe user to select, translate and manipulate free-space floating visualinformation beyond the physical constraints of the device creating theimage. This invention provides a novel augmented reality platform fordisplaying information coexisting spatially as an overlay within thereal physical world. The interactive non-solid free floatingcharacteristics of the image allow the display space to be physicallypenetrable for efficient concurrent use between physical and ‘virtual’activities in multi-tasking scenarios including collaborativeenvironments for military planning, conferencing, and video gaming, aswell as presentation displays for advertising and point-of-salespresentations.

The invention comprises significant improvements over existingnon-physical screens to display clear images, independent of the purelaminar screen found in the prior art, by functioning with non-laminar,semi-laminar and turbulent particle clouds. Novel advancements to themicroenvironment deployment method by means of a multiple stageequalization chamber and baffles generate an even laminar airflowreducing pressure gradients and boundary layer friction between theparticle cloud and the surrounding air. Furthermore, the electronicenvironmental management control (EMC) attenuates particle cloud densityby controlling the amount of particulates generated and ejected inconjunction with the particle cloud exit velocity, thereby ensuring aninvisible to near-invisible screen. This delicate balance of theparticle cloud density and illumination intensity was not possible inthe prior art and therefore the cloud was either highly visible or toolow of a density to generate a bright image. Further advancements toboth an improved projection system improve viewing angle limitationsinherent with prior art such as fluttering caused by turbulence withinthe screen. Furthermore, the invention's self-contained andself-sustaining system is capable of producing a constant stream ofcloud particles by condensing moisture from the surrounding air, therebyallowing the system to operate independently without affecting thegeneral operating environment. Furthermore, the invention incorporatesinteractive capabilities, absent in prior art.

The multiple projection source of this invention has the capacity toproduce multi-imaging; were discrete images projected from varioussources can each be viewed from different locations. This allows aseparate image to be generated and viewed independently from the frontand rear of the display, for use as example in video-gaming scenarios,where opposing players observe their separate “points of view” whilestill being able to observe their opponent through the image. Inaddition, the multisource projection redundancy mitigates occlusion fromoccurring, such as in the prior art, where a person standing between theprojection source and the screen, blocks the image from being displayed.

By projecting from solely one side, the display can also serve as aone-way privacy display where the image is visible from one side andmostly transparent from the other side, something not possible withconventional displays such as television, plasma or computer CRT's andLCD monitors. Varying the projected illumination intensity and clouddensity can further attenuate the image transparency and opacity, afunction not possible with existing displays. Furthermore, since theimage is not contained within a “physical box” comprising a front, flatphysical screen, such as in a conventional display, the image is capableof taking on numerous geometries that are not limited to a flat plane.Furthermore, the dimensions of the image are substantially larger thanthe dimensions of the device creating the image since the image is notconstrained to a physical enclosure such as a convention LCD or CRT. Thedisplay can also take on varying geometric shapes, generating particlecloud surfaces other than a flat plane, such as cylindrical or curvedsurfaces. For these particle cloud types adaptive or corrective opticsallow compensate for variable focal distances for the projection.

Applications for this technology are wide-ranging, since the displayedimage is non-physical and therefore unobtrusive. Imaged information canbe displayed in the center of a room, where people or objects can movethrough the image, for use in teleconferencing, or can be employed as a‘virtual’ heads-up display in a medical operating theater, withoutinterfering with surgery. The system of this invention not only frees upspace where a conventional display might be placed, but due to itsvariable opacity and multi-viewing capability, allows the device to becentered around multiple parties, to freely view, discuss and interactcollaboratively with the image and each other. The device can be hungfrom the ceiling, placed on walls, on the floor, concealed withinfurniture such as a desk, and project images from all directions,allowing the image can be retracted when not in use. A scaled downversion allows portable devices such as PDA's and cell phones to have‘virtual’ large displays and interactive interface in a physically smallenclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the main components and processes of theinvention;

FIG. 2 shows the optical properties of a prior art ball lens, analogousto a single spherical cloud particulate;

FIG. 3 shows the polar angular illumination intensity of each projectionsource;

FIG. 3 a illustrates the one-sided imaging projection embodiment;

FIG. 3 b illustrates the dual-sided concurrent or reversed imagingprojection embodiment;

FIG. 3 c illustrates dual-sided separate imaging projection embodiment;FIG. 4 illustrates the localized optical properties of a single cloudparticulate in a multisource projection arrangement;

FIG. 5 illustrates the optical multisource principle at a larger scalethan presented in FIG. 4;

FIG. 6 represents the imaging clarity level of a single projectionsource;

FIG. 7 represents the imaging clarity level from a multisourceprojection ;

FIG. 8 illustrates the multiple projection source of FIG. 7;

FIG. 9 is a sectional side view of the components of the invention;

FIG. 9 a is close-up of baffle venting for generating microenvironmentof the invention;

FIG. 9 b is a schematic of the environmental management control process;

FIG. 10 illustrates a plan view of multisource projection;

FIG. 11 is an alternate plan view of a single side remote multisourceprojection;

FIG. 12 is an alternate plan view of a dual side individual multisourceprojection;

FIG. 13 illustrates a side view of the detection system of FIG. 9;

FIG. 14 is an axonometric view of the detection system of FIG. 13; and

FIG. 15 illustrates an example of a captured image from the detectionsystem; single click (translation), and double click (selection).

DETAILED DESCRIPTION OF THE INVENTION

The basic elements of invention are illustrated in the FIG. 1 schematic.The preferred embodiment of the invention extracts moisture from thesurrounding air (22) through a heat pump extraction device (1),utilizing solid-state components such as thermoelectric (TEC) modules,compressor-based dehumidification systems or other means of creating athermal differential resulting in condensation build-up for subsequentcollection. Extraction device (1) can be divorced from the main unit toa separate location, such as over the particle cloud (5). The extractedcondensate is stored in a storage vessel (2), which can include anexternal connection (34), for additional refilling or for operationwithout extraction device (1). The condensate is sent to a particlecloud manufacturing system (3), described further in the document, whichalters the condensate by mechanical, acoustical, electrical or chemicalmeans, or a combination of one or more means, into microscopic particlecloud material (5). Particle cloud delivery device (4) ejects themicroscopic particle cloud material locally re-humidifying thesurrounding air (21), creating an invisible to near-invisible particlecloud screen (5), contained within a controlled microenvironment (37).EMC system (18) comprising controller (35) and sensor (36) adjustsscreen (5) density (number of particulates per defined volume), velocityand other parameters of particle cloud (5). External ambient conditionssuch as temperature, humidity, and ambient lighting are read by sensors(36), and sent to controller (35), which interpret the data and instructparticle cloud manufacturing system (3) to adjust the parameters,ensuring an effective invisible to near-invisible screen for imaging.

Signals originating from an external source (12), a VCR, DVD, videogame, computer or other video source, pass through optional scanconverter (38), to processing unit (6), to decode the incoming videosignal. Stored video data (13), contained for example on a hard disk,flash memory, optical, or alternate storage means, can be employed asthe source of content. The processing unit (6), receives these signals,interprets them and sends instructions to graphics board (7), whichgenerates video signal (8), which is sent to an image generating means(9), producing a still or video image. The image generator (9),comprises a means of displaying still or video data for projection,which may be a liquid crystal display, (LCD), digital light processingunit (DLP), organic light emitting diodes (OLED's) or a laser basedmeans of directing or modulating light from any illumination source usedto generate a still or video image. Single image delivery optics (10),comprising telecentric projection optics, may include adaptiveanamorphic optics for focusing onto non-linear screens, such as curvedsurface screens. Components (38, 6, 7, 8, 9, 10) may also be replaced bya video projector in a simplified embodiment. Anamorphic optics anddigital keystone correction are also employed to compensate for off-axisprojection onto non-parallel surfaces.

In the preferred multisource embodiment, a single projection source (9)includes a multi-delivery optical path (20), comprising a series oflenses, prisms, beamsplitters, mirrors, as well as other opticalelements required to split the generated image to “phantom” sourcelocations surrounding the perimeter of the device and redirect theprojection beam onto particle cloud (5). In an alternate multi-imagegeneration embodiment, multiple images are generated on either a singleimage generator, such as one projection unit or a plurality of them(19), and are directed, using a single optical delivery path (10), ormultiple delivery paths using multi-delivery optics (20), splitting andrecombining the projection. Optical or software based means, well knownin the art, or a combination of both means are employed to compensateand correct image focus caused from off-axis projection including imagetrapezoidal keystone correction for one or more axis (i.e. 4 pointkeystoning). In all instances, the directed projection illuminatesparticle cloud (5), where free-space image (11) appears to be floatingin protective microenvironment (37) within the surrounding air (21).Microenvironment (37) functions to increase boundary layer performancebetween the particle cloud and the ambient surrounding air by creating aprotective air current of similar ejection velocity to that of particlecloud (5). This microenvironment (37), and particle cloud (5)characteristics can be continuously optimized to compensate for changingenvironmental conditions, in order to minimize cloud visibility,discussed in further detail below.

In the interactive embodiment, coexisting spatially with image (11) isan input detectable space (39), allowing the image to serve as aninput/output (I/O) device. Physical intrusion within the inputdetectable space (39) of particle cloud (5), such as a user's finger, astylus or another foreign object, is recognized as an input instruction(14). The input is registered when an illumination source (16),comprised of a specific wavelength, such as infrared (IR) source, isdirected towards the detectable space highlighting the intrusion.Illumination comprises a means to reflect light off a physical objectwithin a defined detectable region by utilizing a laser line stripe, IRLED's, or conventional lamp or can include the same illumination sourcefrom the image projection illuminating the detectable space. In itspreferred embodiment, reflected light scattered off the user's finger orother input means (14) is captured by optical sensor (15). Opticalsensor or detector (15) may include a charge-coupled device (CCD),complementary metal-oxide silicon (CMOS) sensor or a similar type ofdetector or sensor capable of capturing image data.

Sensor (15) is capable of filtering unwanted ‘noise’ by operating at alimited or optimized sensitivity response similar to or equal to theillumination source (16) wavelength either by employing a specificbandwidth sensor, utilizing band-pass filters or a combination of both.Light beyond the frequency response bandwidth of the sensor is ignoredor minimized, diminishing background interference and recognizing onlyintentional input (14). The coordinate in space where the intrusion islit by the illumination source corresponds to an analogous two orthree-dimensional location within a computer environment, such as in agraphic user interface (GUI) where the intrusion input (14) functions asa mouse cursor, analogous to a virtual touch-screen. The highlightedsensor captured coordinates are sent to controller (17), that read andinterpret the highlighted input data using blob recognition or gesturerecognition software at processing unit (6), or controller (17).Tracking software coupled for example with mouse emulation softwareinstructs the operating system or application running on processing unit(6) to update the image, accordingly in the GUI. Other detection systemvariations comprise the use of ultrasonic detection, proximity baseddetection or radar based detection, all capable of sensing positionaland translational information.

In its preferred embodiment, this invention operates solely on a powersource independent of a water source by producing its own particle cloudmaterial. By passing the surrounding air through a heat pump, air iscooled and drops below its dew point where condensate can be removed andcollected for the cloud material. One method well known in the artscomprises a dehumidification process by which a compressor propelscoolant through an evaporator coil for dropping the temperature of thecoils or fins and allows moisture in the air to condense while thecondenser expels heat. Another variation includes the use of a series ofsolid-state Peltier TEC modules, such as a sandwich of two ceramicplates with an array of small Bismuth Telluride (Bi₂Te₃) “couples” inbetween, which produce condensation that can be collected on the coldside. Other variations include extracting elements from the ambient airsuch as nitrogen or oxygen, as well as other gases, to manufacturesupercooled gases or liquids by expansion, and as a result, create thethermal gap to generate the condensate cloud material. Another methodincludes electrochemical energy conversion, such as is employed in fuelcell technology, consisting of two electrodes sandwiched around anelectrolyte in which water and electricity are produced. Oxygen passingover one electrode and hydrogen over the other generates electricity torun the device, water for the cloud material and heat as a by-product.

The particle cloud composition consists of a vast number of individualcondensate spheres held together by surface tension with a mean diameterin the one to ten micron region, too small to be visible individually bya viewer, yet large enough to provide an illuminated cloud for imaging.The focus and controlled illumination intensity onto the overall cloud,allow the individual spheres to act as lenses, transmitting and focusinglight at highest intensity on-axis, whereby the viewer positioneddirectly in front of both screen and projection source views the imageat its brightest and clearest. In the multisource embodiment, thedirecting of light from multiple sources onto the particle cloud ensuresthat a clear image is viewable from all around, providing continuouson-axis viewing. The on-axis imaging transmissivity of the cloud screencoupled with the multisource projection insure a clear image, regardlessof the viewer's position and compensates for any aberration caused byturbulent breakdown of the cloud. Intersecting light rays from multiplesources further maximize illumination at the intended image location bylocalizing the sum of illumination from each projection source strikingthe particle cloud imaging location. In this way, the illuminationfalloff beyond the particle cloud is minimized onto unintended surfacesbeyond, as found in prior art where the majority of the light wentthrough the screen and created a brighter picture on a surface beyondrather than on the intended particle cloud. Similarly, multisourceprojection further minimizes the individual projection source luminosityallowing the viewer to view directly on-axis without being inundatedwith a single high intensity projection source, as found in the priorart.

In an alternate embodiment, the particle cloud material can includefluorescence emissive additives or doped solutions, creating an up ordown fluorescence conversion with a specific excitation source,utilizing a non-visible illumination source to generate a visible image.Soluble non-toxic additives injected into the cloud stream at any pointin the process can include for example Rhodamine, or tracer dyes fromXanthane, each with specific absorption spectra excited by a cathode,laser, visible, (ultra-violet) UV or IR stimulation source. Atri-mixture of red, green and blue visibly emissive dyes, each excitedby specific wavelength, generate a visible full spectra image. Theseadditives have low absorption delay times and fluorescence lifetime inthe nanosecond to microsecond region, preventing a blurry image from thedynamically moving screen and generating a high fluorescence yield forsatisfactory imaging luminosity. An integrated or separate aspiratormodule collects the additives from the air and prevents these additivedyes from scattering into the surrounding air.

In prior art, lenticular screens have been utilized to selectivelydirect a predefined image by means of a lens screen so that a particulareye or position of the viewer will render a discrete image. Similarly,when this invention's particle cloud screen is illuminated by anintensity level below where internal refraction and reflection occurwithin each sphere, producing scattered diffused light rays, theindividual particle spheres act as small lenslets performing the similaroptical characteristics of lenticular imaging and allow the cloud toperform as a lenticular imaging system. This concept is furtherexplained in FIGS. 2-7.

FIG. 2 illustrates the optics of an individual cloud particulate,analogous to the optical refractive properties of a ball lens, where Dis the diameter of the near perfect sphere of the particulate formednaturally by surface tension. The incoming light follows along path (E),and at resolution (d), is diffracted as it enters sphere (30), and isfocused at a distance EFL (effective focal length) at point (31),on-axis (E), from the center of the particulate (P), at maximumintensity on axis (31). This process is repeated on adjacentparticulates throughout the depth of the cloud and continues on-axisuntil finally reaching viewer position (110).

On-axis illumination intensity is determined by source intensity and thedepth of the cloud which is represented in polar diagram FIG. 3, wheremaximum intensity and clarity is in front, on-axis at zero-degrees (128)and lowest behind at 180 degrees, (129). These imaging characteristicsoccur when illumination intensity is below saturation illuminationlevels of the particle cloud, that produces omni-directional specularscattering into unintended adjacent particles within the cloud whichunnecessarily receive undesired illumination. Therefore, the floatingimage can be viewed clearly from the front of the screen from arear-projection arrangement and appear invisible, to near invisible,from behind (129) serving as a privacy one-way screen. The cloud, whenviewed from behind, thereby provides an empty surface to project analternate or reversed image for independent dual image viewing fromfront or behind, allowing each separate image to be most visible fromthe opposite end.

FIG. 3 a illustrates the one-sided projection embodiment where viewer(181), observes projection image “A” originating from source or sources(182) towards particle cloud (183). Viewer at location (184) cannotobserve image “A” or at most, a near-invisible reversed image. FIG. 3 bshows image “A” being projected from both sides (185, 186) onto particlecloud (187) where both viewers located at (188, 189) can view image “A”.Projection source or sources at either side can reverse the image sothat for example text can be read from left-to-right from both sides orthe image can correspond so that on one side the image would bereversed. FIG. 3 c shows a dual viewing embodiment where projectionsource or sources (190) project image “A”, while projection source orsources (191), project a discrete image “B”, both onto particle cloud(192). A viewer located at (193) observes image “B” while observer (194)observes image “A”.

FIG. 4 illustrates multisource projection at angle theta, (θ) betweenprojection sources (122, 123) and the particulate (195) providing aconstant on-axis image irrespective of the viewer's location, therebyensuring a clear image. For a viewer positioned at (121), projectedimages following path (145) from projection source (123) are clearlyvisible, while simultaneously projected image rays (144, 145)originating from projection source (122) being projected at angle theta,generate a sum of the intensity of each source. Discrete stereoscopicimages can be projected at angle theta allowing for simulatedthree-dimensional imaging, when distance L₁ is equal or approximatesbinocular distance between the right and left eye of the user and thefalloff of each projection source is great enough so that only thedesired projection source is viewable to the desired left or right eye.

FIG. 5 illustrates the overall view where the viewer is presented withtwo images, either identical or discrete, projected from separate sourcelocations. Light ray (149), from the projection source (124) illuminatesparticle cloud (146), which transmits most of its light on-axis (147)directed to viewer's eye (148). Similarly, a separate or identical imagefrom projection source (125) following light ray (27) illuminatesparticle cloud (146), viewed on-axis (28), when the viewer's eye (29),is directed into the projection axis (28).

FIG. 6 represents the angular clarity falloff of a single projectionsource in a Cartesian coordinate with the maximum intensity and clarityimage on-axis at zero degrees (196). The combination of the individualmicroscopic particulates act as an entire lens array, focusing themajority of light in front of the projection source and on-axisproducing this illumination pattern. These inherent optical propertiesof a particle sphere as well as the particle cloud as a whole insureoff-axis illumination intensity fall-off as a controllable means ofdirecting multiple light paths projecting similar or discrete imagesthat can be viewed from specific locations (on or near on-axis to infront of the projection source).

FIG. 7 shows an example of a multisource projection with three sources,although an n^(th) number of sources are possible. The three sources are(Pa), on-axis at (0), and source (Pb) with clarity threshold at (OT).The angular threshold angle is the midpoint between Pa and on-axis (0)at (126), as well as the midpoint between on-axis (0), and Pb at (127).

FIG. 8 is a plan view of the invention described in the chart of FIG. 7.Source Pa, shown as (24), on-axis source (0) as (25), and source Pb as(26) project onto surface (23) with depth (150). When viewer (152) looksat particle cloud (23), the projection source (26) illuminates themaximum and clearest illuminated image the viewer sees at this locationbecause pixel depth (151) is parallel to the viewing axis (153). Whenthe viewer moves to location (154), the image the he or she sees isilluminated by on-axis projection source (25) where the image projectionis imaged throughout the depth (197) of the particle cloud (150).Similarly, as the viewer moves around particle cloud (150) and whenlocated at position (155), the image viewed originates from source (24).The viewer located at any of these positions or in between will beviewing simultaneously the entire image composed by a plurality ofprojection sources from which the light rays of each sequentially orsimultaneously projected source is directed towards particle cloud(150).

FIG. 9 describes in detail the operation of the preferred embodiment ofthe invention. Surrounding air (156) is drawn into the device (32), byfan or blower (40). This air is passed though a heat exchanger (33, 41),comprising a cold surface such as a thermoelectric cold plate,evaporator fin or coil (33), which can be incorporated or separated asan aspirator (48) located above the particle cloud, serving as acollector. This air subsequentially passes over the hot side of a TECmodule heat sink or condenser coil (41), where heat generated isexhausted into the surrounding air (49), or passes through fans (59,60,) and below to fan (56) so that the exhausted air is of similartemperature. Condensate forming on cold plate, coil or fin (33), dripsvia gravity or forced air and is collected into pan (42), passes throughone-way check valve (50), into storage vessel (43). Alternatively,vessel (43) may allow the device to operate independently, without theuse of a heat exchanger, by opening (44) or other attachment, to fillwith water or connect to external plumbing. A level sensor, optical ormechanical switch controls the heat exchanger, preventing vessel (43)from overflowing. Compressor (157), pumping freon or other coolantthrough pipes (46) and (47) can be employed in a conventionaldehumidification process well known in the art.

Maximizing condensate is critical as it is a high power demandingprocess. Increasing airflow and maximizing surface area of theevaporator are essential for ensuring constant operation and minimizingoverload on the heat exchanger, TEC's or compressor. In a solid-stateTEC embodiment, compressor (45) would be absent and evaporator (33) andcondenser (41) would be replaced by the hot and cold sides of a TECmodule, with appropriate heat sinks to collect moisture on the cold sideand draw heat on the other side. Due to the time lag before condensateformation, vessel (43) allows the device to run for a duration whilecondensate is formed and collected. The stored condensate travels beyondcheck valve (51), controlling the appropriate quantity via sensor orswitch (55) and enters nebulizing expansion chamber (52) for use in theparticle cloud manufacturing process.

In the preferred embodiment, expansion chamber (52) employselectro-mechanical atomizing to vibrate a piezoelectric disk ortransducer (53), oscillating ultrasonically and atomizing thecondensate, generating a fine cloud mist of microscopic particulates forsubsequent deployment. Alternate cloud mist generating techniques can beemployed, including thermal foggers, thermal cooling using cryogenics,spray or atomizing nozzles, or additional means of producing a finemist. The design of the chamber prevents larger particles from leavingexpansion chamber (52), while allowing the mist to form within expansionchamber (52). A level sensor (55), such as a mechanical float switch oroptical sensor, maintains a specific fluid level within expansionchamber (52) to keep the particulate production regulated. When thefluid surface (54) drops, valve (51) opens, thereby maintaining apredefined depth for optimized nebulization.

Fan or blower (56), injects air into chamber (52), mixing with the mistgenerated by nebulizer (53), and the air/mist mixture is ejected throughcenter nozzle (57) at a velocity determined by the height required forcreating particle cloud (58). Furthermore, nozzle (57) can comprise atapered geometry so as to prevent fluid buildup at the lip of nozzle(57). Ejection nozzle (57) may have numerous different shapes, such ascurved or cylindrical surfaces, to create numerous extruded particlecloud possibilities. Particle cloud (58) comprises a laminar,semi-laminar or turbulent flow for deployment as the particle cloudscreen for imaging.

Fans (59 and 60) draw ambient air, or expelled air from the heatexchanger, through vents (61 and 88), comprising baffles, or vents, toproduce a laminar protective air microenvironment (62, 63) envelopingcloud screen (58). For laminar particle cloud screen (58), thismicroenvironment improves boundary layer performance by decreasingboundary layer friction and improving the laminar quality of screen (58)for imaging.

It is important to note that in the prior art, a “Reynolds Number” wasthe determining factor for image quality and maximum size, but becausethis invention integrates multisource projection, the reliance onlaminar quality is diminished. A “Reynolds Number” (R) determineswhether the stream is laminar or not. Viscosity is (u), velocity (V),density (ρ) and thickness of the stream (D) determine the transitionpoint between laminar and turbulent flow, which was the limiting factorin the prior art. Furthermore, the EMC continuously modifies themicroenvironment and particle cloud ejection velocity to compensate fora change in particle cloud density in order to minimize the visibilityof the cloud. The change in particle cloud density affects directly theviscosity of the cloud and therefore the ejection velocities must changeaccordingly to maximize the laminar flow.$R = {\frac{\rho\quad{VD}}{\mu}\quad\left( {{prior}\quad{art}} \right)}$

The ejected particle cloud continues on trajectory (64) along a straightpath producing the particle cloud surface or volume for imaging andeventually disperses at (85) and is not used for imaging purposes.Particulates of screen at (58) return to device (84) to create acontinuous loop system. The particle cloud moisture laded air returnsback into device (84) not impacting the moisture level in the room wherethe device is operating. The density of the cloud is continuouslymonitored for its invisibility by onboard environmental diagnosticsmanagement control EMC (66), which monitors ambient parameters includingbut not limited to, humidity, temperature and ambient luminosity, whichfactors are collected by a plurality of sensors (65). Sensors (65) cancomprise for example, a photodiode or photo-sensor, temperature,barometric as well as other climactic sensors to collect data. Sensorinformation is interpreted by diagnostics management control (66), whichadjusts the density of screen (58) by optimizing the intensity ofparticle cloud manufacturing at (53), and the luminosity of projectionfrom source (69) with respect to ambient humidity and ambient luminosityto control invisibility of the cloud screen (58). A photo-emitter placedon one side of the particle cloud and photo-detector on the oppositeside, can be employed to calculate the visibility of the cloud bymonitoring the amount of light passing from emitter to detector therebymaximizing the invisibility of the cloud.

Images stored on an internal image or data storage device such as CD,programmable memory, CD, DVD, computer (67), or external computer,including ancillary external video-sources such as TV, DVD, or videogame(68), produce the raw image data that is formed on an image generatingmeans (70). Image generating means (70) may include an LCD display,acousto-optical scanner, rotating mirror assembly, laser scanner, or DLPmicromirror to produce and direct an image through optical focusingassembly (71).

Illumination source (69), within an electromagnetic spectrum, such as ahalogen bulb, xenon-arc lamp, UV or IR lamp or LED's, directs a beam ofemissive energy consisting of a mono or polychromatic, coherent,non-coherent, visible or invisible illumination, ultimately towardscloud screen (58). The illumination means can also comprise coherent aswell as polychromatic light sources. In a substitute embodiment theillumination source consists of high intensity LED's or an RGB whitelight laser or single coherent source, where image-generating means (70)operates above or below the visible spectrum. Light directed fromillumination source (69) towards an image generating means (70), passesthrough focusing optics (71), producing light rays (76) directed to anexternal location as a “phantom” delivery source location (77). Phantomsource (77) may employ one or more optical elements including a mirroror prism (83) to redirect or steer the projection (79, 80) towardsparticle cloud (58).

Collimating optics such as a parabolic mirror, lenses, prisms or otheroptical elements may be employed at anamorphic correction optics (77 or78) for compensating projection for off-axis keystoning in one or moreaxis. Furthermore, electronic keystone correction may be employed tocontrol generator (71). Anamorphic correction optics (78) may alsoinclude beam-splitting means for directing the light source passingthrough the image generator to various sources such as source (77)positioned at a location around the perimeter of cloud (58) andcollimate the beam until reaching source (77). Beam splitting can employplate, cube beam-splitters or rotating scanning mirrors with electronicshutters or optical choppers dividing the original source projectioninto a plurality of projections. Projection beams (76) are steeredtowards a single or plurality of phantom sources or locationssurrounding cloud (58) redirecting light rays (79, 80) onto said cloud(58) for imaging. Imaging light rays (81, 82) traveling beyond particlecloud (58) continue to falloff and, caused by the limited depth of fieldrange of optics (71, 78, 83) thereby appear out of focus.

The detection system comprises illumination source (72), directingillumination beam (130) producing a single (131) or dual stripe plane oflight (131, 132), in which an intrusion is captured by optical sensor(86) contained in the cone of vision of the sensor image boundary (133,134) of cloud screen (58). Similarly, two separate sources may beemployed to generate two separate planes or the device may operateutilizing exclusively one plane of light. When foreign object intrusionpenetrates the planar light source (131, 132) parallel to the image,this illumination reflects off the intrusion and is captured by opticalsensor (86). Detected information is sent via signal (135) to computer(67) running current software or operating system (OS) to update theimage generator (70) according to the input information. The device mayalso include user audio feedback for recognizing the selection orinteraction with the non-solid image thereby providing the necessaryuser haptic feedback.

In the preferred embodiment of the invention the detection systemutilizes optical, machine vision means to capture physical intrusionwithin the detectable perimeter of the image, but may employ otherdetection methods. These include for example acoustic based detectionmethods such as ultrasonic detectors, illumination based methods such asIR detectors, to locate and position physical objects, such as a hand orfinger, for real-time tracking purposes. The area in which the image isbeing composed is monitored for any foreign physical intrusion such as afinger, hand, pen or other physical object such as a surgical knife. Thedetectable space corresponds directly to an overlaid area of the image,allowing the image coupled with the detection system to serve as an I/Ointerface that can be manipulated through the use of a computer. Todiminish external detection interference in its preferred embodiment,the detection system relies on an optical detector (86), operating at anarrow band within the invisible spectrum, minimizing captured ambientbackground light illuminating undesired background objects that are notrelated to the user input. The operating detection system wavelengthfurthermore, does not interfere with the imaging and remains unnoticedby the user. The preferred embodiment utilizes a narrow bandwidthillumination source (72), beyond the visible spectrum, such as infrared(IR) or near-infrared (NIR) illumination and subsequentially composedinto a beam by collimating the illumination. The beam generated by aillumination source (72), is sent to one or a plurality of linegenerating means such as employing a line generating cylindrical lens orrotating mirror means to produce a single or dual illuminated plane oflight (73, 74) coexisting spatially parallel to or on top of the imageon cloud (58). This interactive process is described more clearly below.

FIG. 9 a describes the microenvironment generation process in order todeliver a high degree of uniformity to the laminar airflow streamprotecting the cloud, thereby improving image quality dramatically overexisting protective air curtains. A multistage venting or bafflingarrangement of one or more chambers or baffles, vents or meshes, ofvarying sizes and shapes, diminishes micro-variant changes intemperature and velocity between the microenvironment and cloud, therebyminimizing friction and cloud breakdown, thereby improving image qualitydrastically over existing art. The surrounding ambient air or exhaustedair (198) from the heat exchanger passes through means to move this air,such as by an axial, tangential fan or blower (199) housed within anenclosure (200) with sidewalls. Air is mixed into a first-stageequalizing chamber (201) to balance air speed and direction within airspace (202) in enclosure (200). Subsequently the air passes through alinear parallel baffle or vent (203), of length and cell diameter sizedetermined by the Reynolds equation, to produce a laminar airflow inwhich the ejection orifice end (233), and injection orifice end (234)are colinear with the laminar airflow microenvironment (235).Simultaneously, the particle cloud laminar ejection, thin walled nozzle(204) ejects particle cloud material towards the exterior (205) into thelaminar airflow microenvironment (235). Since there are invariablysubtle differences in temperature and velocity between the cloud andmicroenvironment, the two airflows pass through a final equalizationchamber (206) to further stabilize, before being ejected into the air(205). Further equalization can be achieved by offsetting baffles, sothat adjacent cells share airflow, minimizing airflow velocitygradients. Exterior ejection baffle or vents (207) are thin in thicknessand depth in order to prevent condensate buildup, allowing for extendeduse.

FIG. 9 b illustrates the main processes involved in maintaining a highfidelity image suspended in free-space, by minimizing cloud visibilityand reducing fluttering due to particle cloud turbulence. Environmentalsensors (209) monitor surrounding air (208). Sensors include, but arenot limited to ambient temperature sensors (210), such as solid-statethermo-resistors, to gauge temperatures. Similarly, relative humiditysensor (211) and ambient luminosity sensor (212), such as aphoto-detector gather additional data (211), such as binary, resistive,voltage or current values. Data (211) is sent to controller (214)comprising of electronic hardware circuitry to gather the separatesensor value information to create a composite sum value correspondingto the amount of absolute or relative change as signal (228) for futureuse in modifying parameters of the particle cloud.

Signal (228) attenuates particle cloud manufacturing density (216) bycontrolling the amount of particulates generated by regulating thesupply voltage or current to the ultrasonic atomizer. Similarly, thesignal (228) can vary the outlet opening of particulates escaping theexpansion chamber thereby controlling the amount of particulates (217),ejected into the cloud (221). Since the amount of particulates ejectedis directly proportional to the viscosity as defined in ReynoldsEquation, modifying the particulate density (the amount of material intothe air) requires a proportional change in both particle cloud ejectionvelocity (218) and microenvironment ejection velocity (219). Signal(228) controls this ejection velocity by varying fan speed, such as byutilizing pulse width modulation to alter exit velocities of particlecloud (221) and microenvironment (220).

Augmenting these detectors, or operating as a separate unit, a cloudvisibility detector (224) comprising an illumination source (222), suchas a photo emitter or laser and corresponding photo detector (223), suchas a Cadmium sulfide photocell. Both detector (223) and illuminationsource (222), each disposed at opposite ends of the particle cloud arearranged so as to gather a known quantity of light from the illuminationsource (222) passing through the particle cloud (221) which is receivedby the opposite detector. The loss in signal strength to the lightreflected off particle cloud (221) and not received by detector (223)corresponds to the density and therefore visibility of the cloud. Thissignal (225) can be sent to controller (214) to regulate density andvelocity modifying visibility of cloud (221). Similarly, another methodincludes, an airborne particulate counter (226) to acquire particulateair sample data within the particle cloud (221) to determine theparticle count corresponding to the density or visibility of particlecloud (221). Particulate data (227) is sent to controller (214),instructing (228), to adjust particle cloud manufacturing (216) and exitvelocities (215) in the same way as the previously described methods.

FIG. 10 shows the top view of the multi-source embodiment of theinvention where the main projection (90) and optics (91, 92, 104, 105,106, 107) are part of the main unit (93). Image projection originatesfrom imaging generator (90) consisting of a high frame rate projector,Liquid Crystal Display (LCD), Digital Light Processing (DLP) unit, orother aforementioned methods, directed towards collimating optics (91)towards beam splitting mechanism (92). In a solid-state embodiment,these optical elements comprise a series of prisms, and, or beamsplitters to gradually divide the original beam into numerous beams,well understood in the art. In the case of an infinite number of beamsplitting capabilities, the original beam is directed towards a singleor multi-faceted rotating scanner (104) redirecting the beam towards aplurality of sources such as (101, 102, 103). A photo interrupter (105),such as an optical chopper or electronic shutter, is necessary to createconsecutive image segments, in a fashion similar to a conventionalreel-to-reel movie projector moving through its frames. Furtheranamorphic optical assemblies (106, 107) correct for off-axisprojection, either as part of the main imaging unit (93) or atindividual sources (101, 102, 103). The anamorphic optics and keystonecorrection in all embodiments insure that the projection beams (229,230, 231) directed at, and illuminating particle cloud (232) used in aidentical projection scenario, each project and focus the same imagefrom each source are focused at the same location on particle cloud(232).

FIG. 11 shows a top view of another multi-source embodiment where theprojection and optics (158) are separated from the main unit (94).Imaging source (95) directs light to beam re-directing means (96). Beamre-directing means (96) comprises a method to steer or reflect incomingprojection from imaging unit (95) and may consist of cube beamsplitters, plate beam splitters, mirrors, wedge prisms or scanningmirrors. The projection is sent to phantom sources (97, 98, 99) wherethe image is composed onto cloud (100). FIG. 12 demonstrates a thirdembodiment where each projection source (136, 137, 138, 139, 140, 141)is a separate unit projecting onto cloud (142). In another variation,fiber optics can be employed to transfer image projection to eachsource.

The detection system is isolated for clearer explanation in FIGS. 13through 15. In the preferred embodiment of the invention, FIG. 13 showsthe isolated detection system shown in FIG. 9 and means to capture userinput, using an optical detector, sensor or camera such as CCD or CMOSdetector (159), using lens or bandwidth filters (160). Capture means(159) captures solely reflected illumination within the image boundarywithin defined image range (162, 164), of particle cloud (163).

An illumination source (167), with a spectral output similar to thefrequency response of the detector, such as an IR laser projecting abeam through a line generator and collimator (166), reflect off beamsplitter (176) towards mirror (165) and mirror (108), into two separateIR light planes (109 and 177). Line generating techniques, well known inthe art to create a plane of light, such as those employing rotatingmirrors or cylindrical lenses, such as Ohmori's U.S. Pat. No. 5,012,485can be employed are employed at (108, 165). Finger (111) intersects withbeam (109) reflecting light back to detector (159) for real-timecapture. Similarly, finger (112) intersecting both beams (109 and 177),reflects two separate highlights captured by detector (159). In anotherembodiment each detectable light plane functions at a differentwavelength. Similarly, the invention can operate using a singledetectable light plane and utilize dwell software, well-known in theart, or create a selection by penetrating the plane twice in rapidsuccession to “double click”, as in a computer OS.

FIG. 14 shows an axonometric view of FIG. 13. Illumination sources suchas a laser diode (171) direct light towards collimator (170), passingthrough a means to split the beam, such as a beamsplitter (178).Similarly, the illumination source can comprise projection sourceillumination (172) or collimated IR LED's parallel to the particlecloud. Split beams directed to plane generating means, such as rotatingmirrors (179, 180) create double detection beam planes (168, 169).Finger (119) intersects parallel detection beam planes (79 and 80),centered at location x, y, z in three-dimensional space. Detector (173)captures the highlighted intersection either as a two-axis coordinates,or by combining two separate detectors or sensors provides a third axisfor tracking positional information. This information is sent tocontroller (174) and is interpreted by a processor or computer CPU (175)using an operating system or software. Blob recognition software,coupled with mouse emulation driven software well known in the art,translates the captured pixels as addressable coordinates within adesktop environment or application, to allow the user to navigate freelyusing a finger or stylus. Software such as those designed byNaturalPoint, Xvision, Smoothware Design may be employed to interpretthe captured data to operate the software driven interface in a mousestyle environment. Similarly, gesture recognition or voice recognitionmeans can be employed to augment the input interface.

FIG. 15 is an example of a user input light reflection captured by thedetection system when finger (113) intersects at (114) first detectionbeam (118). The illumination reflects off finger (113) and is capturedby optical sensor (143) stimulating corresponding pixels of opticalsensor (143) represented as (115). The center of the crescent pixels(115) corresponds to a user input at point (116), which representing thex and y coordinates. In a similar fashion, when finger (117) intersectsboth detection beams (118, 120), the highlighted double crescent iscaptured by the detector. Moving the user's finger on the surface of theimage, thereby skimming the image surface, allows the user to navigateusing a finger as a virtual touch-screen interface. When the userrequires selecting, the equivalent of double clicking on a typical OS,the intrusion or finger must proceed further into the image as ifselecting it, similar to pushing a button.

While a description of the preferred embodiment of the present inventionhas been given, further modifications and alterations will occur tothose skilled in the art. It is therefore understood that all suchmodifications and alterations be considered as within the spirit andscope of the invention as defined by the appended claims.

1. A system for creating a free-space display comprising a heat pump,means to introduce ambient air through the heat pump, means to create athermal differential in the heat pump, means to extract condensate fromthe ambient air using the thermal differential, means to pass thecondensate into an expansion chamber, means to atomize the condensate inthe expansion chamber to create particle cloud material, ejection nozzlemeans to eject the particle cloud material into the air to create aparticle cloud screen, means to eject a parallel laminar air streamenclosing the particle cloud, means to generate an image or images,projection means to project an image or images onto the particle cloudscreen.
 2. A system for creating a free-space display comprising a heatpump, means to introduce ambient air through the heat pump, means tocreate a thermal differential in the heat pump, means to extractcondensate from the ambient air using the thermal differential, means topass the condensate into an expansion chamber, means to atomize thecondensate in the expansion chamber to create particle cloud material,ejection nozzle means to eject the particle cloud material into the airto create a particle cloud screen, means to eject a parallel laminar airstream enclosing the particle cloud, means to generate an image orimages, projection means to project an image or images onto the particlecloud screen, detection means located adjacent to the particle cloudscreen and adapted to capture intrusion within or adjacent to theprojected image, means to read the location of each intrusion, means tosend the intrusion location information to a controller, means to modifythe image generator means in response to the intrusion locationinformation.
 3. The system of claim 1 or 2 in which the heat pumpcomprises a compressor based reverse-cycle cooling dehumidificationsystem.
 4. The system of claim 1 or 2 in which the heat pump comprises athermoelectric Peltier-junction based system.
 5. The system of claim 1or 2 in which heat pump comprises a fuel cell or means to use cooledgases or liquids.
 6. The system of claim 1 or 2 further comprising aholding vessel for collection of the condensate.
 7. The system of claim1 or 2, further comprising means to atomize the condensate into amicroscopic particle cloud of individual particulates with a meandiameter of 1 to 10 microns.
 8. The system of claim 1 or 2, furthercomprising means to atomize the condensate into a microscopic particlecloud of individual particulates with a mean diameter greater than 10microns.
 9. The system of claim 1 or 2, in which the atomization meanscomprises electro-mechanical or ultrasonic means.
 10. The system ofclaim 1 or 2 further comprising fluorescence tracers or dyes in theparticle cloud.
 11. The system of claim 1 or 2, further comprising aco-linear ejection nozzle to eject the particles into the air to createa co-linear ejected particle cloud.
 12. The system of claim 11comprising an ejection nozzle of a geometry corresponding to the depthand width of the particle cloud screen, where the third dimension is theextruded particle cloud ejection distance.
 13. The system of claim 1 or2, in which the ejected particles generate a laminar, semi-laminar orturbulent particle cloud.
 14. The system of claim 1 or 2, in which theparticle cloud comprises an invisible, near invisible or visibleparticle cloud.
 15. The system of claim 1 or 2, in which the particlecloud comprises a medium to reflect, refract and transmit light orimages from a projection source directed at said particle cloud.
 16. Thesystem of claim 1 or 2, in which the particle cloud comprises a mediumwith a higher transmissive illumination coefficient than a reflectiveand refractive illumination coefficient.
 17. The system of claim 1 or 2in which the means to create the laminar airflow comprises parallellinear baffles, vents, meshes or a combination thereof with fans orblowers disposed at the opposite orifice end of the laminar airflow. 18.The system of claim 17 in which the means to create the laminar airflowcomprises a series of stacked parallel, linear baffles, vents, or mesheswith the fan or blower at one orifice end, and laminar airflow at theother orifice end.
 19. The system of claim 18 further comprising asingle air space or plurality of air spaces between the baffles, vents,or meshes, to create a velocity equalization chamber.
 20. The system ofclaim 1 or 2 further comprising means to monitor the visibility of theparticle cloud screen.
 21. The system of claim 20 further comprisinglight emitting means and light detecting means directed towards eachother, with the particle cloud between the light emitting means andlight detecting means to measure the light transmissivity andreflectivity of the particle cloud screen.
 22. The system of claim 21 inwhich the light emitting means comprises a light emitting diode or laserand the light detecting means comprises a photo-detector.
 23. The systemof claim 20 further comprising an ambient particulate counter to monitorthe particulate count of the particle cloud screen.
 24. The system ofclaim 20 further comprising means to monitor the ambient humidity,ambient temperature and ambient luminosity.
 25. The system of claim 20in which responsive to the monitored data environmental managementcontrol means regulates the ejection velocity of the particle cloudmaterial, the particle cloud manufacturing intensity, or a combinationthereof to maximize particle cloud invisibility.
 26. The system of claim25 in which the environmental management control means regulatesejection velocity by utilizing fan speed control means.
 27. The systemof claim 1 or 2 in which the image generating means creates a still orvideo image.
 28. The system of claim 27 further comprising utilizingpolarized, random, coherent, visible or invisible wavelengths of lightcombined with the image generating means to create an image projector.29. The system of claim 27 in which said image-generating meanscomprises a liquid crystal display, digital light processing panel,organic light emitting diode, optical modulation or a laser scanner. 30.The system of claim 1 or 2 comprising a single projector means directedand aligned towards the particle cloud screen for imaging.
 31. Thesystem of claim 1 or 2 comprising a plurality of projectors directedtowards the particle cloud screen for imaging.
 32. The system of claim 1or 2 further comprising a single projector or plurality of projectorswhich comprise optical or electronic anamorphic keystone imagingdistortion correction for one or more axis.
 33. The system of claim 1 or2 further comprising optical means to collimate a projection beamtowards a phantom source, said optical means comprising beam steering orreflecting means surrounding the particle cloud, that redirect theprojection beam onto said particle cloud.
 34. The system of claim 1 or 2further comprising a single projector or plurality of projectors whichcomprise optical or electronic anamorphic keystone focal distancecorrection for one or more axis.
 35. The system of claim 1 or 2comprising a single projection means, means to direct a projection beamtowards a single or plurality of phantom sources, said means to directthe projection beam comprising beam steering or reflecting meanssurrounding the particle cloud that redirect the beam towards saidparticle cloud.
 36. The system of claim 35 comprising multipleprojection beam-splitting, beam-steering, beam-beam chopping or acombination thereof to divide the projection image into a plurality ofprojection beams.
 37. The system of claim 36 further comprising beamsplitters, polka dot splitters, band-pass filters, wedge prisms, prisms,static mirrors, rotating mirrors, digital light processing, electronicor physical shutters, optical choppers, or a combination thereof tosplit the projection beam into a plurality of beams aimed towards aplurality of phantom redirecting sources surrounding the particle cloud.38. The system of claim 1 or 2 comprising means to project identicalimages or discrete images from discrete or identical sources towards theparticle cloud to compose similar or discrete images on said particlecloud.
 39. The system of claim 2 further comprising a visible orinvisible illumination source directed at the particle cloud region foruser input tracking.
 40. The system of claim 39, in which theillumination source comprises a halogen lamp, incandescent lamp, lightemitting diode or laser.
 41. The system of claim 40 in which theillumination source produces light in the infrared or near infraredspectrum.
 42. The system of claim 2 in which the means to detectphysical intrusion within the particle cloud comprises machine vision,optical capturing means comprising optical detectors and sensors, videocameras, complementary metal-oxide silicon sensors, or charged coupleddevices.
 43. The system of claim 42 further comprising a band-passfilter.
 44. The system of claim 39 comprising a single illuminationdetection plane.
 45. The system of claim 39 further comprising aplurality of illumination detection planes.
 46. The system of claim 44or 45 further comprising cylindrical lenses, collimating lenses,rotating faceted mirrors, or a combination thereof, to compose a singleor plurality of detection planes.
 47. The system of claim 2 comprising aplurality of detectors to track user input intrusion within the particlecloud in two or three-dimensional space.
 48. The system of claim 42further comprising means to communicate illuminated, detected positionaldata to a controller, processor or computer.
 49. The system of claim 42further comprising motion-tracking software to interpret illuminated,detected positional data to navigate within software applicationenvironments or graphic user environments.
 50. The system of claim 49 inwhich the tracking software comprises blob recognition, crescentrecognition or gesture recognition software.
 51. The system of claim 49further comprising noise filtering software.
 52. The system of claim 49further comprising navigation utilizing mouse emulation software. 53.The system of claim 49 comprising means to modify the projectiongenerating means in response to the illuminated detection positionaldata registered by the detector, coupled with tracking software runningmouse emulation software or navigation software to direct the operatingsystem or software application controlling the projection software. 54.The system of claim 2 comprising a computer running tracking softwareprojector content, for controlling the image projectors.
 55. The systemof claim 1 or 2 further comprising an aspirator disposed at the end ofthe particle cloud trajectory, to collect condensate and means totransfer the condensate to the expansion chamber for particle cloudmanufacturing.
 56. The system of claim 55 further comprising a heat pumpwith the aspirator.
 57. A method for creating a free-space displaycomprising dehumidifying air, capturing the humidity, atomizing thehumidity to create particle cloud material one to ten microns indiameter, ejecting the particle cloud material to create a particlecloud, surrounding the particle cloud with a parallel laminar air streammicroenvironment of equal or similar velocity and trajectory to theparticle cloud, generating an image or images, projecting the image orimages onto the particle cloud.
 58. A method for creating an interactivefree-space display comprising dehumidifying air, capturing the humidity,atomizing the humidity to create particle cloud material one to tenmicrons in diameter, ejecting the particle cloud material to create aparticle cloud, surrounding the particle cloud with a parallel laminarair stream microenvironment of equal or similar velocity and trajectoryto the particle cloud, generating an image or images, projecting theimage or images onto the particle cloud, detecting an intrusion withinor adjacent to the free-space display by detecting said intrusion tocreate trackable data and using the trackable data to computationallyupdate the projection of the image.
 59. The method of claim 57 or 58further comprising splitting the projected image or images into aplurality of projection beams, redirecting the plurality of projectionbeams and focusing said projection beams onto the particle cloud tocreate a free-space image.
 60. A method for creating an interactivefree-space display comprising dehumidifying air, capturing the humidityand ejecting it to re-humidify the air to create a surface or volumeparticle cloud comprising individual one to ten micron mean diameterparticulates, surrounding the particle cloud with a microenvironment ofequal or similar velocity, illuminating said cloud using an illuminationsource, passing the illumination onto, reflecting or passing through animage generating means to split projected images into a plurality ofprojection beams, redirecting projection beams and focusing saidprojection image from projection means onto the particle cloud toreflect, refract, and transmit light to generate a free-space image,detecting the intrusion of a physical object within or adjacent to thefree-space image by video capture means by illuminating said intrusionand detecting said illumination in order to create trackable data andusing the trackable data as input to computationally update theprojection means.
 61. The method of claim 57 or 58 comprising generatinga differential temperature drop of 10 degrees or more Celsius betweenthe heat pump and ambient air to extract condensate from the ambientair.
 62. The method of claim 57 or 58, further comprising ejecting alaminar airflow microenvironment surrounding one or more parallel sidesof said particle cloud screen to enhance boundary layer performancebetween the particle cloud screen and ambient air.
 63. The method ofclaim 62 in which the laminar airflow microenvironment velocity andtrajectory is the same or similar in velocity and trajectory to that ofthe particle cloud.
 64. The method of claim 60, in which the detectionillumination coexists spatially and parallel to the particle cloud imageregion.
 65. A system for creating a free-space display comprising acompressor-based condensing system to extract condensate from air, aholding vessel for collecting the condensate, an opening in the holdingvessel for introduction of additional liquid, an atomizer to generate aparticle cloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the particle cloudinto the air, baffles or vents parallel to and spaced from the ejectionnozzle, fans disposed adjacent to the baffles or vents to blow airthrough the baffles or vents, enclosing the particle cloud with parallelairstreams, light emitters and light detectors directed towards eachother with the particle cloud in between to monitor the visibility ofthe particle cloud, a system for controlling the quantity of ejectedparticle cloud based upon the monitoring of the visibility of theparticle cloud, an image projector directed towards and illuminating theparticle cloud, to generate an image upon the particle cloud.
 66. Asystem for creating a free-space display comprising a thermo-electriccondensing system to extract condensate from air, a holding vessel forcollecting the condensate, an opening in the holding vessel forintroduction of additional liquid, an atomizer to generate a particlecloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the cloud into theair, baffles or vents parallel to and spaced from the ejection nozzle,fans disposed adjacent to the baffles or vents to blow air through thebaffles or vents, enclosing the particle cloud with parallel airatreams,light emitters and light detectors directed towards each other with theparticle cloud in between to monitor the visibility of the particlecloud, a system for controlling the quantity of ejected particle cloudbased on the monitoring of the visibility of the particle cloud, animage projector directed towards and illuminating the particle cloud, togenerate an image upon the particle cloud.
 67. A system for creating aninteractive free-space display comprising a compressor-based condensingsystem to extract condensate from air, a holding vessel for collectingthe condensate, an opening in the holding vessel for introduction ofadditional liquid, an atomizer to generate a particle cloud ofcondensate in an expansion chamber, an ejection nozzle connected to theexpansion chamber to eject the particle cloud into the air, fansconnected to the expansion chamber to move the particle cloud into theair, baffles or vents parallel to and spaced from the ejection nozzle,fans adjacent to the baffles or vents to blow air through the baffles orvents, enclosing the particle cloud with parallel arstreams, lightemitters and light detectors directed towards each other with theparticle cloud in between to monitor the visibility of the particlecloud, a system for controlling the quantity of ejected particle cloudbased upon the monitoring of the visibility of the particle cloud, animage projector directed towards and illuminating the particle cloud,light emitters to create one or more planes of light parallel to orcoplanar with the particle cloud, optical sensors to detect physicalintrusion within the planes of light, position-tracking software totrack physical intrusion in the planes of light for controlling theimage projection within a graphic user environment.
 68. A system forcreating an interactive free-space display comprising a thermo-electriccondensing system to extract condensate from air, a holding vessel forcollecting the condensate, an opening in the holding vessel forintroduction of additional liquid, an atomizer to generate a particlecloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the particle cloudinto the air, baffles or vents parallel to and spaced from the ejectionnozzle, fans disposed adjacent to the baffles or vents to blow airthrough the baffles or vents, enclosing the particle cloud with parallelairstreams, light emitters and light detectors directed towards eachother with the particle cloud in between to monitor the visibility ofthe particle cloud, a system for controlling the quantity of ejectedparticle cloud based upon the monitoring of the visibility of theparticle cloud, an image projector directed towards and illuminating theparticle cloud, light emitters to create one or more planes of lightparallel to or coplanar with the particle cloud, optical sensors todetect physical intrusion within the planes of light, position-trackingsoftware to track physical intrusion in the planes of light forcontrolling the image projection within a graphic user environment. 69.A system for creating a free-space display comprising a compressor-basedcondensing system to extract condensate from air, a holding vessel forcollecting the condensate, an opening in the holding vessel forintroduction of additional liquid, an atomizer to generate a particlecloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the particle cloudinto the air, baffles or vents parallel to and spaced from the ejectionnozzle, fans disposed adjacent to the baffles or vents to blow airthrough the baffles or vents, enclosing the particle cloud with parallelairstreams, light emitters and light detectors directed towards eachother with the particle cloud in between to monitor the visibility ofthe particle cloud, a system for controlling the quantity of ejectedparticle cloud based upon the monitoring of the visibility of theparticle cloud, an image projector directed towards a plurality ofmirrors to split and redirect the projected image towards locationssurrounding the particle cloud and focus the projected image onto theparticle cloud.
 70. A system for creating free-space display comprisinga thermo-electric condensing system to extract condensate from air, aholding vessel for collecting the condensate, an opening in the holdingvessel for introduction of additional liquid, an atomizer to generate aparticle cloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the cloud into theair, baffles or vents parallel to and spaced from the ejection nozzle,fans disposed adjacent to the baffles or vents to blow air through thebaffles or vents, enclosing the particle cloud with parallel airstreams,light emitters and light detecors directed towards each other with theparticle cloud in between to monitor the visibility of the particlecloud, a system for controlling the quantity of ejected particle cloudbased on the monitoring of the visibility of the particle cloud, animage projector directed towards a plurality of mirrors to split andredirect the projected image towards locations surrounding the particlecloud and focus the projected image onto the particle cloud.
 71. Asystem for creating free-space display comprising a compressor-basedcondensing system to extract condensate from air, a holding vessel forcollecting the condensate, an opening in the holding vessel forintroduction of additional liquid, an atomizer to generate a particlecloud of condensate in an expansion chamber, an ejection nozzleconnected to the expansion chamber to eject the particle cloud into theair, fans connected to the expansion chamber to move the particle cloudinto the air, battles or vents parallel to and spaced from the ejectionnozzle, fans disposed adjacent to the baffles or vents to blow airthrough the baffles or vents, enclosing the particle cloud with parallelairstreams, light emitters and light detectors directed towards eachother with the particle cloud in between to monitor the visibility ofthe particle cloud, a system for controlling the quantity of ejectedparticle cloud based upon the monitoring of the visibility of theparticle cloud, an image projector directed towards a plurality ofmirrors to split and redirect the projected image towards locationssurrounding the particle cloud and focus the projected image onto theparticle cloud, light emitters to create one or more planes of lightparallel to or coplanar with the particle cloud, optical sensors todetect physical intrusion within the plane of light, position-trackingsoftware to track physical intrusion into the plane of light forcontrolling the image projection within a graphic user environment. 72.A system for creating a free-space display comprising a thermo-electriccondensing system to extract condensate from air, a holding vessel forcollecting the condensate, an opening in the holding vessel forintroduction of additional liquid, an atomizer to generate a particlecloud of condensate in an expansion chamber, an expansion chamber, anejection nozzle connected to the expansion chamber to eject the particlecloud into the air, fans connected to the expansion chamber to move thecloud into the air, baffles or vents parallel to and spaced from theejection nozzle, fans disposed adjacent to the baffles or vents to blowair through the baffles or vents, enclosing the particle cloud withparallel airstreams, light emitters and light detectors directed towardseach other with the particle cloud in between them to monitor thevisibility of the particle cloud, a control system for the atomizer tocontrol particle cloud conditions based on the monitoring of thevisibility of the particle cloud, an image projector directed towards aplurality of mirrors to split and redirect the projected image towardslocations surrounding the particle cloud and focus the projected imageonto the particle cloud, light emitters to create one or more planes oflight parallel to or coplanar with the particle cloud, optical sensorsto detect physical intrusion within the plane of light,position-tracking software to track physical intrusion in the plane oflight for controlling the image projection within a graphic userenvironment.
 73. A method for creating a free-space display comprisingcondensing moisture from air and ejecting the moisture into the air togenerate a particle cloud and projecting images onto the particle cloud.74. A method for creating a free-space display comprising condensingmoisture from air and ejecting the moisture into the air to generate aparticle cloud and projecting images onto the particle cloud from aplurality of sources surrounding the particle cloud.
 75. A method forcreating an interactive free-space display comprising condensingmoisture from air and ejecting the moisture into the air to generate aparticle cloud and projecting images onto the particle cloud, andtracking the position of physical intrusion adjacent to or within theparticle cloud for controlling the image projection within a graphicuser environment.
 76. A method for creating an interactive free-spacedisplay comprising condensing moisture from air and ejecting themoisture into the air to generate a particle cloud and projecting imagesonto the particle cloud from a plurality of sources surrounding theparticle cloud, and tracking the position of physical intrusion adjacentto or within the particle cloud for controlling the image projectionwithin a graphic user environment.
 77. A method for creating afree-space display comprising condensing moisture from air and ejectingthe moisture into the air to generate a particle cloud and projectingseparate stereo images onto the particle cloud.
 78. A method forcreating an interactive free-space display comprising condensingmoisture from air and ejecting the moisture into the air to generate aparticle cloud and projecting separate stereo images onto the particlecloud, while tracking the position of physical intrusion adjacent to orwithin the particle cloud for controlling the image projection within agraphic user environment.
 79. A method for creating a free-space displaycomprising condensing moisture from air and ejecting the moisture intothe air to generate a particle cloud and projecting intersecting beamsfrom a plurality of sources onto the particle cloud.
 80. A method forcreating a free-space display comprising condensing moisture from airand ejecting the moisture into the air to generate a particle cloud andprojecting intersecting beams from a plurality of sources onto theparticle cloud, while tracking the position of physical intrusionadjacent to or within the particle cloud for controlling the projectionwithin a graphic user environment.